ABSTRACT
In previous studies the authors have investigated several methods, which relied on the measurement of the dielectric parameters, to estimate the amount of water in samples of granular materials, and adapted these methods to calculate the moisture content of wheat seeds. These studies have been developed by simultaneously measuring one (ε') or two (ε' and ε") dielectric parameters at two frequencies or the measurement of those two parameters at a single frequency. However, the resulting calibration equations did not allow a density-independent estimation of moisture content to be made with the expected degree of accuracy. These are the only alternatives that could be used, besides the use of a costly g-ray density gauge, in order to reduce or eliminate the deleterious effect of bulk density on the calculated value of moisture content. The density-independent determination of moisture content is a fundamental pre-requisite for the development of on-line moisture meters. Thus, the objective of this research was to investigate in more detail the factors involved in the indirect estimation of wheat moisture content by adapting to radio frequencies the method originally developed by Meyer & Schilz (1980) to measure moisture content of granular materials using microwave frequencies. The resulting equation was capable of estimating wheat moisture content with standard errors of calibration and prediction of 0.3 and 0.4-percentage point moisture, respectively.
Key words:
instrumentation; radiofrequency; moisture content